his defense team insists that his wife died of natural causes. several medical witnesses are expected to take the stand today in what is expected to be another dramatic day in this murder trial. alicia acuna is live from our denver bureau with more on this. >> reporter: hi, jenna. we're hearing from a forensic pathologist, an expert witness who was hired by the prosecution. some people know him as the medical examiner from florida who performed the autopsy on anna nicole smith. he testified he was brought on to the case and given tissue sample slides and autopsy reports of michelle macneill to study. take a listen. >> my opinion was michele died as a result of drowning and in addition to that she had some drugs which were not in fox kohl logical levels but, in my opinion, could have contributed to her death. >> reporter: she was found in a bathtub in her home fully clothed by her 6-year-old daughter in 2007. her death was initially ruled natural causes as a result of cardiovascular disease. that was amended by utah's chief medical examiner to und